According to polls conducted in the years after World War II, what Americans most feared next to nuclear war was polio(myelitis), although more people died because of an accident or of cancer. But polio was contagious and hit without warning, children more often than adults, causing paralysis and frequently death. There were epidemic years when in the US the average count of about 20,000 polio cases per year more than doubled (e.g. 1952 – 58,000), and research into possible cures had been ongoing since the 1930s. By the late 1940s it was clear that there were three types of poliovirus. By 1950, the Polish-American virologist Hillary Koprowski (1916-2013) of the Lederle Laboratories in New York had developed a vaccine containing an attenuated live form of these three viruses, which, taken orally, would activate enough antibodies, according to preliminary tests, to confer initial immunity. Yet more testing was needed.

Meanwhile, Dr. Jonas Salk (1914-1995) of the Virus Research Laboratory, University of Pittsburgh School of Medicine, had followed a different approach. Funded by the National Foundation for Infantile Paralysis (better known by “the March of Dimes”, their fundraising program), an organisation founded with the help of President Franklin D. Roosevelt (himself a victim of polio), Dr. Salk eventually developed a vaccine of inactivated viruses that would be injected and secure increasing immunity with each refreshment dose (3 in all). By 1952 he was ready to test it out. After some early successful trials (including tests on himself and his family), Salk divulged the positive results over the radio, appealing to the public to participate in the necessary further test cycle.

On 23 February, 1954, the vaccine began to be publicly tested, first at the Arsenal Elementary School and the Watson Home for Children in Pittsburgh, Pennsylvania, and then at a number of other public institutions, eventually involving over 1.8 million children in 14 states. More than half of these served as a control group, and the other divided into ‘placebo’ children and ‘vaccinated’ children – one of the largest medical experiments in history. The results – affirmative – were announced in April 1955, and as soon as the vaccine was licensed that same year, mass campaigns secured its rapid nationwide application.

By the early 1960s Dr. Albert Sabin (1906-1993), who had further developed and tested Dr. Koprowski’s vaccine, had his oral alternative ready for commercialisation. It would eventually be the preferred choice of both children and adults. By 1961, the benefits of the anti-polio vaccine were indisputable: in the US, the number of recorded polio cases had fallen to 161.